Our long term goal is to provide a framework to understand how a simple, innate behavior emerges from the activity of the nervous system. For this, we will apply a battery of molecular genetics techniques and imaging technologies to study the circuit mechanisms underlying temperature preference in Drosophila -a system ideally suited for a comprehensive genetic and molecular dissection of neural circuits and behaviors. We have recently shown that temperature is represented by a map of activity created by sensory afferents at the first relay station in the fly brain. We now propose to study how this map is processed by central neural circuits and transformed into directed behavior. To accomplish our overall objectives, we will use a combination of targeted photo-activation of GFP, GRASP, ChR2-mediated circuit mapping and genetic expression of effector molecules to: 1) Identify ascending neuronal populations receiving temperature information and representing it to higher brain centers. 2) Study their tuning and properties, and narrow our search to the key pathways that mediate temperature navigation and preference. 3) Determine their connectivity to higher brain centers, study the transformation of stimuli at each station in the circuit and eventually track the descending pathways that control behavior. This work is expected to contribute to our general understanding of the wiring logic of the neural circuits that control innate behavior in animals, and potentially provide insights on how genetic conditions which affect wiring can result in compromised circuit function and altered behavior.